Manufacture of artificial silk



means.

EMILE :enonnnn'r, on numaausnn, seamen.

MANUFACTURE or ARTIFICIAL 51m.

Eo Drawing.

To all whom it may concern:

Be it known that I, EMILE BRONNERT, a citizen of the Republic of France,residing at Quai du Barrage, Mulhausen, Alsace-Lor raine, France, haveinvented certain new and useful Improvements in the Manufacture ofArtificial Silk, of which the following is a specification (for which Ifiled applications in Germany, filed May 19th, 1919; Czecho-Slovakia,filed April 12th, 1920; Belium, England, France, Netherlands, Italy,orway, Austria, Sweden, Switzerland, Spain, and Hungary, filed April30th, 1920).

This invention has reference to an im proved process for the manufactureof very fine threads of highly lustrous viscose silk.

In the manufacture of artificial threads of viscose, there have beenused in the past baths containing aldehyde bisulphites, oxymethyl esterof sulphurous acid, the reduc tion products whereof, such assulphooxylates, ketone bisulphites, or also condensation products.from'phenols or naphthols on the one side and aldehydes and sulphites onthe other side with or without the addition of organic salts or sugartypes.

As heretofore used these baths were only calculated for the ordinaryartificial silk, with individual threads of about 7 to 8 deniers. Thisis apparent from the fact, that the known process makes no provision forany of the recently discovered essential steps in the process whichenable threads of almost any desired fineness to be obtained when usingordinary spinning apertures of about 0.10 mm. diameter, Apart from theexact regulation of the feed of viscose to the apertures of constantsize, according to the number of threads and the total titer desired,the concentration of the baths is more especially of--prime importance.

As to th' 'o oncentration of the baths, however in' the case ofbisulphite nothing has been Known up to the present.

somewhat difi erent' from those existing in Specification of LettersPatent. I

I hate found that the finer it is desired, to s in the more concentratedmust be the bisu phite solution. These conditions are- Patented Judy it,1 922.

Application filed August 31, 1920. Serial No. 407,252.

sulphuric acid in which the concentration must generally be inverselyproportional to the square roots of the thread in denier figures.

With bisulphite baths a barely sufiicient coagulative power, exists,only at a relatively high concentration; but this coagulation thenincreases rapidly. For instance, with a concentration of 310 gr.bisulphite per litre, a thread of 7.5 deniers can be spun, but not athread of 2 deniers, while with 360 gnbisulphite per-litre, a thread ofabout 2 deniers can be produced.

This highest possible concentration of 360 gr. per litre'must not bediminished by additions of for example aqueous formaldehyde, but must bemaintained for instance by the addition of solid bisulphite. Thisconcentration does not sufiice for the perfect spinning of still finerthreads such for instance as such of from 1 to 1-3; deniers. For suchthread finenesses recourse must be had to the more easily solublebisulphite of ammonium and solid salt together with an increasedtemperature, in order to secure a suitable concentration.

With lower concentrations and more especially with coarser singlethreads, the thread issuing from the bath remains brown and soluble inwater.

With a higher concentration and finer single or individual threads thesebecome more and more opalescent, doubtless in conse uence of theinception of decomposition.

iscose having'a ripeness of about 8.5 (chloride of ammonium standard)with about 400 mm. spinning length and a speed of approximately 40m. .isperferably employed with these baths. The fixing is ef-- fected, whennecessary with acid salts, corresponding to about 5% free acid, ordirectly with acid.

What I claim is: l. The step in the process of producing very fineviscose silk threads of 6 deniers or through the 'usual aperture of 0.10 mm.

less, which consists in forcing the viscose diameter into a precipitantbath containing a concentrated solution of easily soluble bisul bites,the concentration of the bath being irectly proportional to the finenessof the thread to be produced, so that the-com centration is increased inaccordance with 5 the fineness of the thread desired.

2. The process according to claim 1, charthreads of 7 deniers andupward, as 10 forth in the specification.

In witness whereof, I have hereunto signed my name in the presence oftwo subscribing witnesses.

EMILE BRONNERT. Witnesses:

L. R. DE SAms, N. G. HAMBERGER.

